GB757698A - Aerating apparatus and method particularly for froth flotation processes - Google Patents

Abstract

757,698. Aerating pulp; froth flotations. MINING PROCESS & PATENT CO. Dec. 18, 1952, No. 32140/52. Classes 82(2) and 86. A method of aerating a body of pulp of substantial depth in a confined treatment zone subject to continuous feed and discharge, more especially for froth flotation treatment, includes the steps of subjecting the pulp in a lower portion of the zone to a centrifugally induced flow, during which agitation and aeration of the pulp and a beating of the aerated pulp causing it to rise in the zone is effected, and subjecting a portion of the thus aerated pulp in an upper portion of the zone to a centrifugally induced flow during which further aeration and agitation of the said portion of the pulp is effected. Known froth-flotation reagents are used. In Fig. 1, the centrifugal circulation in the lower part of the zone C is induced by a rotary squirrel cage impeller R on a rotary shaft 18 having air ducts 47. The pulp is circulated through openings 49, 51 in the bottom and top discs 45, 44 of the impeller R is agitated and aerated by the action of the squirrel cage bars, 46, and the aerated pulp is subject to a beating action by the bars 43 of a stationary enclosure E. Pulp which is not sufficiently aerated to float to the surface is recirculated for further aeration and agitation by a rotary impeller 37 mounted on the shaft 18 which draws such pulp through holes 41 in a hollow column 33 which carries a stationary hood 35 carrying vanes 36 surrounding the impeller 37. The aerating gas is supplied to the hollow shaft 18, and to the hollow column 33 from a header 28. The bars of the squirrel cage rotor may be inclined, Figs. 5-10 (not shown) in order to impart to the pulp, components of movement in an upward, or in an upward and downward direction. Several impellers in series may be provided in a single tank T, the flow of pulp through the tank from an inlet 22 to an outlet 23 being controlled by inclined partitions 54 and transverse partitions 55. In a modification, Fig. 3, also having a squirrel cage lower impeller R<SP>1</SP>, the upper impeller consists of upper and lower rotary members 86, 87 separated by a stationary partition 85 the upper member having openings 88 through which the recirculated aerated pulp is drawn into the impeller. In a further modification, Fig. 4, the upper and lower impellers are part of a single unit which is divided by a centrally apertured partition member, which may be a stationary partition 138 or may be a partition 148 formed integrally with the impeller unit. The bore in the impeller shaft may extend through the lower end of the shaft as shown in Figs. 1 and 4 whereby aerating gas is discharged between the bottom of the lower impeller and the bottom of the tank for admixture with pulp entering the lower impeller.